Surprising reasons you're tired all the time

We all tend to blame fatigue on a too-busy lifestyle. And much of the time we’re right.

If you feel tired all the time, don’t blow it off. Give yourself about 2 to 3 weeks to make some lifestyle changes. Get more sleep, trim your social calendar, eat more wholesome foods, drink more fluids, take a multivitamin, and cut back on caffeine and alcohol.

"If you're still feeling the symptoms of fatigue after those changes, then you need professional help," says Sandra Adamson Fryhofer, MD, an internal medicine doctor in Atlanta. Excess exhaustion could be the sign of a more serious medical condition that can be treated. Here are the 7 most common problems to know about.

This condition is more common in women with heavy periods or who don’t consume enough iron.

The fatigue caused by anemia is the result of a lack of red blood cells, which bring oxygen from your lungs to your tissues and cells. You may feel weak and short of breath. Anemia may be caused by an iron or vitamin deficiency, blood loss, internal bleeding, or a chronic disease such as rheumatoid arthritis, cancer, or kidney failure. Women of childbearing age are especially susceptible to iron-deficiency anemia because of blood loss during menstruation and the body's need for extra iron during pregnancy and breastfeeding, explains Laurence Corash, MD, adjunct professor of laboratory medicine at the University of California, San Francisco.

The symptoms: Fatigue is a major one. Others include extreme weakness, difficulty sleeping, lack of concentration, rapid heartbeat, chest pains, and headache. Simple exercise, such as climbing the stairs or walking short distances, can cause fatigue.

The tests: A thorough evaluation for anemia includes a complete physical exam and blood tests, including a complete blood count (CBC), to check the levels of your red blood cells. It's also standard to check the stool for blood loss.

More than a million people are diagnosed with type 2 diabetes every year, but many more may not even know they have it.

Sugar, also called glucose, is the fuel that keeps your body going. And that means trouble for people with type 2 diabetes who can't use glucose properly, causing it to build up in the blood. Without enough energy to keep the body running smoothly, people with diabetes often notice fatigue as one of the first warning signs, says Christopher D. Saudek, MD, professor of medicine and program director for the General Clinical Research Center at the Johns Hopkins University School of Medicine.

The tests: There are two major tests for diabetes. The fasting plasma glucose test, which is more common, measures your blood glucose level after fasting for 8 hours, usually first thing in the morning. With the oral glucose tolerance test (OGTT), blood is drawn twice: just before drinking a glucose syrup, then 2 hours later.

When your thyroid hormones are out of whack, even everyday activities will make you feel wiped out.

The thyroid gland, about the size of the knot on a man's tie, is found in the front of the neck and produces hormones that control your metabolism. Too much thyroid hormone (hyperthyroidism), and metabolism speeds up. Too little (hypothyroidism), and metabolism slows down.

The symptoms: Hyperthyroidism causes muscle fatigue and weakness, which you may notice first in the thighs. Exercises such as riding a bike or climbing stairs become more difficult. Other symptoms include unexplained weight loss, feeling warm all the time, increased heart rate, shorter and less frequent menstrual flows, and increased thirst. Hyperthyroidism is most commonly diagnosed in women in their 20s and 30s, but it can occur in older women and men too, says Robert J. McConnell, MD, codirector of the New York Thyroid Center at Columbia University Medical Center in New York City.

Hypothyroidism causes fatigue, an inability to concentrate, and muscle soreness, even with minor activity. Other symptoms include weight gain due to water retention, feeling cold all the time (even in warmer weather), heavier and more frequent menstrual flows, and constipation. Hypothyroidism is most common in women over age 50. In fact, as many as 10% of women past 50 will have at least mild hypothyroidism, says McConnell.

The tests: Thyroid disease can be detected with a blood test. "Thyroid disorders are so treatable that a thyroid test should be done in all people who complain of fatigue and/or muscle weakness," says McConnell.

4. Depression

More than "the blues," depression is a major illness that affects the way we sleep, eat, and feel about ourselves and others.

Without treatment, the symptoms of depression may last for weeks, months, or even years. So it's important to recognize the warning signs and get help.

The symptoms: We don't all experience depression in the same way. But commonly, depression can cause decreased energy, changes in sleeping and eating patterns, problems with memory and concentration, and feelings of hopelessness, worthlessness, and negativity.

The tests: There’s no blood test for depression, but your doctor may be able to identify it by asking you a series of questions. If you experience five or more symptoms below for more than 2 weeks, or if they interfere with your life, see your doctor or mental health professional. Your doctor may also recommend a thorough physical exam to rule out other issues.

Persistent physical symptoms that don't respond to treatment, such as headaches, chronic pain, or constipation and other digestive disorders

Difficulty concentrating, remembering, or making decisions

Feeling guilty, hopeless, or worthless

Thoughts of death or suicide

5. Rheumatoid Arthritis

This autoimmune disease is not always easy to diagnose early, but there are some subtle clues to look for.

RA happens when your immune system turns against itself and attacks healthy joint tissue, sometimes resulting in irreversible damage to bone and cartilage.

The symptoms: Many symptoms (such as fatigue, low energy, loss of appetite, and joint pain) are shared by other health conditions, including other forms of arthritis such as fibromyalgia and lupus. Also, anemia and thyroid disorders, which also cause fatigue, are even more common in people with RA, according to John Klippel, MD, president and CEO of the Atlanta-based Arthritis Foundation.

Rheumatologists look for at least four of the following criteria in diagnosing RA: morning stiffness in and around the joints lasting at least 1 hour before maximum improvement; at least three joint areas with simultaneous soft tissue swelling or fluid; at least one joint area swollen in a wrist, knuckle, or the middle joint of a finger; simultaneous involvement of the same joint areas on both sides of the body; lumps of tissue under the skin; and bone erosion in the wrist or hand joints, detected by x-ray.

The tests: A thorough physical exam by a rheumatologist can provide some of the most valuable evidence of the disease, but there is also a test for the presence of rheumatoid factor, an antibody found in the blood. About 80% of people with RA test positive for this antibody, but the test is not conclusive.

You could have this sleep-disrupting problem if you wake up feeling tired no matter how much rest you think you got.

Sleep apnea is a disorder characterized by brief interruptions of breathing during sleep. In the most common type, obstructive sleep apnea, your upper airway actually closes or collapses for a few seconds, which, in turn, alerts your brain to wake you up to begin breathing again. Someone with obstructive sleep apnea may stop breathing dozens or even hundreds of times a night, says Roseanne S. Barker, MD, former medical director of the Baptist Sleep Institute in Knoxville, TN.

The symptoms: Sleep apnea is often signaled by snoring and is generally followed by tiredness the next day. Because sleep apnea can lead to heart disease, high blood pressure, and stroke, it's important to be tested.

The tests: This involves an overnight stay at a sleep clinic, where you'll undergo a polysomnogram, which is a painless test that will monitor your sleep patterns, breathing changes, and brain activity.

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